P0340 is back

Matt14 said:

Thanks guys. I feel confidentish lol in my skills but also don’t know if I have the time if things go wrong since this is my daily driver.

Is it normal for this to go bad at 140,000? Feels really early. Just want to make sure this is even the right route.

Does this make sense to you guys. “Checked cam/crank data. Shows they are off by 3 degrees. Removed cam Syncro cover and found that there is excessive play in Syncro. Removed distributer and found that drive gear has been worn down over time and there is excessive play in the timing chain. Can replace timing chain and condition will improve *but if distributor gear is worn too much, DTCs may set in the future*.”

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If that is from the shop, the problem is not your timing set, it is the OPDA gear and possibly the cam gear.

OPDA gear wear is a know 05 and 06 issue. If the OPDA (passenger side of engine where the distributor used to be) is an LDI unit, it needs to be swapped out for a Crown or Dorman unit. The cam gear needs to be inspected for wear.

Oh, and to answer your question, I have 250K on the timing set on my 06, so 140K is way early for a timing chain to go assuming the engine has been properly maintained.

JKP said:

If that is from the shop, the problem is not your timing set, it is the OPDA gear and possibly the cam gear.

OPDA gear wear is a know 05 and 06 issue. If the OPDA (passenger side of engine where the distributor used to be) is an LDI unit, it needs to be swapped out for a Crown or Dorman unit. The cam gear needs to be inspected for wear.

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Do the crown unit, the dorman is also known to fail.

Thank you! @rasband @JKP

I replaced the OPDA with the Dorman unit about 2 year ago and about 30,000 miles ago. So could this all just be the OPDA went bad again? It isn’t making the “screaming monkey” noise at the moment.

Also, if I had them do the timing chain which is more involved, is it OK if I just do the OPDA myself when I get it back or do they need to be done at the same time?

Matt14 said:

Thank you! @rasband @JKP

I replaced the OPDA with the Dorman unit about 2 year ago and about 30,000 miles ago. So could this all just be the OPDA went bad again? It isn’t making the “screaming monkey” noise at the moment.

Also, if I had them do the timing chain which is more involved, is it OK if I just do the OPDA myself when I get it back or do they need to be done at the same time?

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It's worth just opening the cap and pulling up on the internal piece. A local guy sent this on his dorman opda - so any vertical movement will tell you what you need to know here.

I don't see any reason you need to do the both at the same time aside from if they have a DRBIII which allows them to put the PCM back into "learn" mode on the timing.

Pull your OPDA and check the gear and make sure the thrust wash hasn't been worn away like the one in the photo above.

If the gear is worn again, you need to check the cam gear for wear. A worn cam gear will eat a new OPDA gear in short order.

I've put 135K on my Dorman OPDA and it's fine. I pull it to check it every so often.

JKP said:

Oh, and to answer your question, I have 250K on the timing set on my 06, so 140K is way early for a timing chain to go assuming the engine has been properly maintained.

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That's not entirely correct.

My TJ is correctly maintained and the TC was stretched as per the video at 220 000km (that's 136 000miles) Symptoms were at far less mileage than that.

Its still running like a dream BTW.

Daz7 said:

That's not entirely correct.

My TJ is correctly maintained and the TC was stretched as per the video at 220 000km (that's 136 000miles) Symptoms were at far less mileage than that.

Its still running like a dream BTW.

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Wow, I guess you can get a bad one.

My '92 was over 275K when I changed it.

JKP said:

Wow, I guess you can get a bad one.

My '92 was over 275K when I changed it.

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I feel the older 4.0's get away with things because they don't have all of the sensors hanging off them like the 05/06's.

What's happening is we're getting chain stretch, throwing sensor codes (going into limp home mode) and whilst trying to diagnose the issue we generally retime the OPDA (Cam sensor) to the stretched chain in the hope of fixing the issue.

It's sort of getting around the problem but isn't really and its why the codes come back.

This is conformed when replacing the TC but not touching the OPDA. My TJ started throwing 0016 codes, cam position sensor (CMP) is out of sync with the crankshaft position sensor (CKP).

Retime the OPDA to the new chain and it's all good. The problem with diagnosing this, is that errors point to electronic/sensor problems. So everyone goers down that rabbit hole. The 4.0 also runs fine even when throwing codes, just the ECU goes into limp home mode or throws the 0344 or 0340 code and engine light.

Matt14 said:

I am having a lot of the same issues you guys are having and I couldn't figure it out. So I took it to a shop, and they said it was the timing chain as well. I haven't decided if I will do it myself or have them do it yet. Any thoughts on this estimate? Is this reasonable? I saw @Daz7 said it took him about 4-5 hours. Can anyone else weigh in on how hard it is?


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I did mine last spring. It’s a pretty straight forward job with a lot of extra work. Removing belts and harmonic balancer and stuff. I did the water pump and flushed my radiator and stuff while I was in there. Took me at least 5 hours because I pulled my radiator out completely to get at the harmonic balancer. It definitely made my 2.5l run better.

Does reflashing the pcm also set the timing to tdc?

Sorry, after thinking more on it I see it can't.

So, back in September I thought about some info I read here about advancing the "timing" by rotating the OPDA a few degrees to make up for any slack in the timing chain. So, I did that. The code has never returned and the Jeep has been a dream since then. With almost 250K on the motor I still plan to get inside, but not until I have time next year. For now, she runs great.

I changed the oil and replaced a quart of oil with a quart of MMO. I expected the oil darken as the MMO did it's thing. But, the oil even after 750 miles is clean and clear. Oil pressure is great. Valvetrain tick is still there. Comes and goes with RPM but is not there at idle. Comes in at about 1000 and quiets down a little over 2000. The MMO expereiment will be terminated next weekend then back to regular stuff and a fresh filter.